As another Vietnam Vet I know a little about this. There are several things the VA looks at. First, the record of units and areas of operation that you were assigned to and operated in while in country. The records of where geographically and on what dates the Ranch hand program sprayed not only Agent Orange, but also agent white and other toxins/carcinogens are well documented. The records of unit movements in these areas in the years afterwards are also there. If your records do not show that you were in the mix, geographically and time-wise, you will not qualify. The primary cancer that dioxin is associated with is Lymphoma, and ironically enough Admiral Zumwalt, who was in charge of the program and ordered the spraying, had a son who was a brown water sailor who died of lymphoma right after the war as a result of the use of Agent Orange. While I will not argue that the government screwed us all for years (while they were waiting for their army to die before admitting complicity and responsibility), there have also been a bevy of vets with cancers that have no relationship to these defoliants trying to get in on the benefits (crappy as they are). People who have smoked heavily since the years of the war and now have lung cancer will have a hard time getting a claim approved in spite of their service. It would seem that even in this case where there are real people who were harmed by this policy of defoliant use, there are also those who would like to not take responsibility for their lifestyle choices, or other precipitating factors to their disease. Oral cancers are seldom the first cancer of choice for these Agent Orange carcinogens to initiate. Tonsilar and oropharangeal cancers are heavily tied to viral exposure, and I am living proof of this. If use the search tool and the word Vietnam, you will read old posts regarding this same subject.